I don't know what size your Super D is, but I use a Lowepro Rezo 190 AW, interior dimensions about 12" wide, 6" deep, 7.5" high. It's just fine for my 3x4 RB along with roll-film back, light meter etc. This is a discontinued model I got for the amazing sale price of $25! (In the current LowePro stock look at the interior dimensions of the ProMessenger AW 180 or 200). Expensive, so it might be worthwhile having a look at secondhand equipment.
The 3x4 Model B with 2x3 roll-film holder is my favorite portrait camera. The uncoated 6-3/8" lens has a good focal length on 2x3, and my subjects like the gentle image quality.